Activate Phyrexian Altar by sacrificing Reassembling Skeleton, adding {B}
When Reassembling Skeleton dies, Teysa triggers, creating a 1/1 white Spirit creature token
Activate Phyrexian Altar by sacrificing the Spirit, adding one mana of any color.
Activate Reassembling Skeleton by paying {1}{B}, returning it from your graveyard to the battlefield.
Repeat

Infinite creature LTB

Infinite creature ETB

Infinite creature sacrifice triggers

Infinite death triggers

Teysa, Orzhov Scion

Phyrexian Altar

Reassembling Skeleton

Activate Viscera Seer by sacrificing another creature.
When the creature dies, Teysa triggers, creating a 1/1 Spirit creature token that is black due to Darkest Hour.
Resolve the Viscera Seer ability.
Repeat.

Darkest Hour

Viscera Seer

Activate Phyrexian Altar by sacrificing Nether Traitor, adding {B}.
When Nether Traitor dies, Teysa triggers, creating a 1/1 Spirit creature token.
Activate Phyrexian Altar by sacrificing the Spirit, adding one mana of any color.
When the Spirit dies, Nether Traitor triggers, causing you to pay {B} to return Nether Traitor from your graveyard to the battlefield.
Repeat.

Infinite colored mana

Nether Traitor

Activate Teysa by sacrificing three other creatures, targeting any creature.
When the creatures die, Teysa triggers three times, creating three 1/1 Spirit creature tokens that are black due to Painter's Servant.
Repeat.
Resolve all Teysa abilities, exiling the targeted creature(s).

Exile all creatures opponents control

Painter's Servant

Activate Teysa by sacrificing three Angels, targeting any creature.
When the Angels die, Bishop of Wings' second ability triggers three times.
Resolve the first trigger, creating a 4/4 Angel creature token due to Divine Visitation.
When the Angel enters the battlefield, Bishop of Wings' first ability triggers, causing you to gain 4 life.
Repeat from step 3 for each remaining trigger.
Repeat from step 1.
Resolve all Teysa abilities, exiling the chosen creature(s).
You may also repeat this loop whenever a creature enters the battlefield under an opponent's control.

Exile all creatures that enter the battlefield under an opponent's control

Infinite lifegain

Infinite lifegain triggers

Bishop of Wings

Divine Visitation

Cast Alter Reality by paying {1}{U}, changing all instances of "white" on Teysa to "black".
Activate Teysa by sacrificing three black creatures, targeting any creature.
The creatures die, triggering Teysa three times, creating three 1/1 black Spirit creature tokens.
Repeat from step 2.

Alter Reality

Cast Whim of Volrath by paying {U}, changing all instances of "white" on Teysa to "black".
Activate Teysa by sacrificing three black creatures, targeting any creature.
The creatures die, triggering Teysa three times, creating three 1/1 black Spirit creature tokens.
Repeat from step 2.

Whim of Volrath

Cast Sleight of Mind by paying {U}, changing all instances of "white" on Teysa to "black".
Activate Teysa by sacrificing three black creatures, targeting any creature.
The creatures die, triggering Teysa three times, creating three 1/1 black Spirit creature tokens.
Repeat from step 2.

Sleight of Mind

Cast Mind Bend by paying {U}, changing all instances of "white" on Teysa to "black".
Activate Teysa by sacrificing three black creatures, targeting any creature.
The creatures die, triggering Teysa three times, creating three 1/1 black Spirit creature tokens.
Repeat from step 2.

Mind Bend

Cast Crystal Spray by paying {2}{U}, changing all instances of "white" on Teysa to "black" until end of turn, and causing you to draw a card.
Activate Teysa by sacrificing three black creatures, targeting any creature.
The creatures die, triggering Teysa three times, creating three 1/1 black Spirit creature tokens.
Repeat from step 2.

Combos with "Teysa, Orzhov Scion"